兔骨髓线粒体中一种对寡霉素耐药的镁离子依赖性ATP酶。

An oligomycin-resistant Mg2+-dependent ATPase in rabbit bone marrow mitochondria.

作者信息

Abou-Khalil S, Abou-Khalil W H, Yunis A A

出版信息

Mol Cell Biochem. 1982 Apr 16;44(1):33-8. doi: 10.1007/BF00573843.

Abstract

Rabbit bone marrow mitochondria isolated by differential centrifugation showed typical oxypolarographic tracings with glutamate oxidation with ADP:O ratio of 2.9. Similar results were obtained with liver mitochondria of the same animal. When marrow mitochondria were oxydizing a substrate such as glutamate, added MgCl2 markedly stimulated state-4 respiration giving a respiratory rate identical to that of state-3. In contrast, no Mg2+-stimulation was observed with liver mitochondria. Oligomycin completely blocked the stimulation by Mg2+ but further addition of 2,4-dinitrophenol reactivated the oxygen consumption by uncoupling. Further purification of marrow mitochondria by density gradient centrifugation in Percoll provided identical oxypolarographic results. Moreover, when marrow mitochondria were incubated without Mg2+, they showed a low ATPase activity that was stimulated by 2,4-dinitrophenol and blocked by oligomycin. The presence of Mg2+ in the incubation medium uncovered an additional ATPase activity which was resistant to oligomycin and apparently unaffected by 2,4-dinitrophenol. It is concluded that bone marrow mitochondria possess two types of ATPase activity distinguished on the basis of their reactivity with oligomycin, 2,4-dinitrophenol and Mg2+.

摘要

通过差速离心分离得到的兔骨髓线粒体，在以谷氨酸为底物进行氧化时呈现典型的氧极谱图，其ADP:O比值为2.9。对同一动物的肝脏线粒体进行检测也得到了类似结果。当骨髓线粒体氧化谷氨酸等底物时，添加的MgCl₂显著刺激了状态4呼吸，使其呼吸速率与状态3相同。相比之下，肝脏线粒体未观察到Mg²⁺刺激作用。寡霉素完全阻断了Mg²⁺的刺激作用，但进一步添加2,4-二硝基苯酚通过解偶联作用使氧消耗重新激活。通过在Percoll中进行密度梯度离心对骨髓线粒体进行进一步纯化，得到了相同的氧极谱结果。此外，当骨髓线粒体在无Mg²⁺条件下孵育时，它们表现出较低的ATP酶活性，该活性可被2,4-二硝基苯酚刺激并被寡霉素阻断。孵育培养基中Mg²⁺的存在揭示了另一种ATP酶活性，该活性对寡霉素具有抗性，且显然不受2,4-二硝基苯酚的影响。由此得出结论，骨髓线粒体具有两种基于其对寡霉素、2,4-二硝基苯酚和Mg²⁺反应性而区分的ATP酶活性。